Mechanical Efficiency of Hydraulic Air Compressors

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Valeria Pavese ◽  
Dean Millar ◽  
Vittorio Verda
Keyword(s):  
Bubbly Flow ◽  
Mechanical Efficiency ◽  
Open Loop ◽  
Economic Implication ◽  
Intimate Contact ◽  
Air Compressor ◽  
Design Variables ◽  
Gas Compression ◽  
Large Heat ◽  
Air Compressors

After air and water mixing, the process of gas compression in the downcomer shaft or pipe of a hydraulic air compressor is considered nearly isothermal due to (i) the mass flow rate of water being typically of three orders higher than that of the gas it compresses, (ii) water having a heat capacity approximately four times that of air, and (iii) the intimate contact and large heat transfer area between the gas phase and the liquid phase of the bubbly flow. A formulation for estimation of the efficiency of a closed- or open-loop hydraulic air compressor, expressed in terms of the principal hydraulic air compressor design variables, is presented. The influence of a hitherto underappreciated factor affecting the performance of these installations, such as the solubility of the gas being compressed in the water, is explored. A procedure for estimating the yield of compressed gas, accounting for these solubility losses, is explained and used to determine the mechanical efficiency of historical hydraulic air compressor installations from reported performance data. The result is a significant downward revision of hydraulic air compressor efficiency by approximately 20% points in comparison to most reported efficiencies. However, through manipulation of cosolute concentrations in the water, and the temperature of the water (through regulation of the ejection of compression heat), the mechanical efficiency can be increased to the formerly reported levels. The thermo-economic implication of these efficiency determinations is that in a modern context, hydraulic air compressors may be able to outperform conventional mechanical gas compression equipment.

Normalisation of Test Results in Air Screw Compressor Measurements as a Basis for Performance Estimation of Refrigeration and Process Gas Compressors

2011 ◽  
Author(s):  
Nikola Stosic
Keyword(s):  
Air Conditioning ◽  
Ideal Gas ◽  
Performance Estimation ◽  
Screw Compressor ◽  
Test Results ◽  
Process Gas ◽  
Scale Factors ◽  
Gas Compression ◽  
Air Compressors ◽  
Real Fluids

Common use of screw compressors is in compression of air. However, application of screw compressors in refrigeration and air conditioning, as well as in process gas compression is increasing rapidly in recent years. The existing experimental data basis for air compressors may conveniently serve as a source for performance estimation of these compressors. A procedure was derived in this work to find scale factors which connect compressors operating with different fluids and it was applied for performance estimation of refrigeration and process gas screw compressors on the basis of measurements obtained for air compressors. Refprop 8 by NIST was used for calculation of thermodynamic properties of real fluids and ideal gas relation was used for air.

Kinematic Design of a 5-DOF Hybrid Robot with Large Workspace/Limb–Stroke Ratio

2006 ◽  
Vol 129 (5) ◽  
pp. 530-537 ◽  
Author(s):  
Haitao Liu ◽  
Tian Huang ◽  
Jianping Mei ◽  
Xueman Zhao ◽  
Derek G. Chetwynd ◽  
...  
Keyword(s):  
Kinematic Chain ◽  
Open Loop ◽  
Singular Value ◽  
Dimensional Synthesis ◽  
Output Link ◽  
Design Variables ◽  
Spherical Parallel Mechanism ◽  
Symmetry Requirement ◽  
The Mean ◽  
Spherical Mechanism

This paper deals with the conceptual and kinematic designs of a 5-degree of freedom (DOF) reconfigurable hybrid robot. The robot is composed of a 2-DOF parallel spherical mechanism that is serially connected with a 3-DOF open loop kinematic chain via a prismatic joint. Somewhat similar to the well-known Tricept robot, this design has the merit that a relatively large workspace/limb–stroke ratio can be achieved thanks to the decomposition of the motions of the output link into the 2-DOF rotation and 1-DOF translation. As with the Tricept, the robot is well suited for use as a plug-and-play module to configure different machines. The dimensional synthesis of the 2-DOF spherical parallel mechanism is carried out by the monotonical analysis of the design variables versus a global conditioning index represented by the mean of the minimum singular value of the Jacobian, leading to the solution of two nonlinear equations due to the limb length constraint and nearly axial symmetry requirement of the kinematic performance. The results of the dimensional synthesis are given via examples.

Miniature Air Compressor Design Based on Cross-Slider Mechanism

2011 ◽  
Vol 486 ◽  
pp. 17-20 ◽  
Author(s):  
Gil Jun Lee ◽  
Suk Hwan Chi ◽  
Jay Kim ◽  
Tae Soo Lee
Keyword(s):  
Time History ◽  
Ideal Gas ◽  
Connecting Rod ◽  
Air Compressor ◽  
Flow Capacity ◽  
Pressure Time ◽  
Compressor Design ◽  
Scotch Yoke Mechanism ◽  
Air Compressors ◽  
Crank Mechanism

Most of the current air compressors are driven by a slider-crank mechanism consisted of the crank, connecting rod, and piston. Complexity of this mechanism, however, restricts miniaturization of air compressors. In this study, a design based on a new mechanism, a hybrid of cross-slider and scotch-yoke mechanism, is adopted to develop an oil-free, light-weighted air compressor for portable medical devices. By eliminating the connecting rod, the mechanism has several advantages in addition to the obvious weight reduction due to the simpler mechanism such as the longer seal life of the seal between the piston and cylinder (so called Teflon cup) and reduced shaking forces. Cylinder pressure time history is obtained based on the ideal gas behavior and the isentropic process. Shaking forces and motor torque are calculated from the dynamics equation of the air compressor. The flow capacity curve of the air compressor is obtained by considering the effect of the clearance volume. An actual prototype was fabricated and tested to demonstrate the feasibility of proposed concepts.

scholarly journals Response optimization of underactuated vibration generators through dynamic structural modification and shaping of the excitation forces

2020 ◽  
Vol 112 (1-2) ◽  
pp. 505-524
Author(s):  
Roberto Belotti ◽  
Dario Richiedei ◽  
Iacopo Tamellin ◽  
Alberto Trevisani
Keyword(s):  
Open Loop ◽  
Analytical Sensitivity ◽  
Inverse Dynamic ◽  
Harmonic Vibrations ◽  
Inertial Parameters ◽  
Design Variables ◽  
Analytical Sensitivity Analysis ◽  
Response Optimization ◽  
Spatial Shape ◽  
Linear Vibratory Feeder

AbstractResonant vibration generators, such as vibratory feeders or ultrasonic sonotrodes, are often employed in manufacturing to generate harmonic vibrations with suitable amplitude, spatial shape, and frequency, in order to meet the process requirements. These underactuated systems are usually excited in open loop by few actuators, and therefore, it is not ensured that the desired response is correctly achieved, since the feasible motions should belong to the subset of the allowable motions. To achieve the closest approximation of the desired vibrations, some new solutions are here proposed. The first strategy is the optimal shaping of the harmonic forces exerted by the actuators, by solving an inverse dynamic problem through a coordinate transformation and the projection of the desired response onto the subspace of the allowable motion. By exploiting the formulation of such a subspace, a second approach that involves concurrently both the force shaping and the modification of the inertial and elastic system parameters is proposed. The idea of this approach is to exploit the modification of the elastic and inertial parameters to properly shape the allowable subspace in such a way that it spans the desired response. A solution method is developed, and analytical sensitivity analysis is proposed to choose the design variables. Validation is proposed through a linear vibratory feeder with a long flexible tray, taken from the literature. The results show the effectiveness of the proposed strategies that lead to a very precise approximation of the desired response.

Mechanical Efficiency Optimization of a Sliding Vane Rotary Compressor

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Yuan Mao Huang ◽  
San Nan Tsay
Keyword(s):  
Genetic Algorithms ◽  
Major Axis ◽  
Mechanical Efficiency ◽  
Rotary Compressor ◽  
Friction Forces ◽  
Efficiency Optimization ◽  
Design Variables ◽  
Axis Length ◽  
Further Development ◽  
Polytropic Exponent

This study presents the mechanical efficiency optimization of a sliding vane rotary compressor by using genetic algorithms. Relevant air properties, volume segments, vane loadings and stresses, friction forces, compression power, and power loss are calculated to determine the mechanical efficiency of a compressor. Design variables include the major axis length and minor axis length of the elliptical stator inner contour, thickness, depth and width of vanes, mechanical efficiency, rotor rotational speed, polytropic exponent, and angular locations of the inlet and outlet ports. The effects of the mutation rate, crossover rate, and population size of the genetic algorithms on these design variables are studied. The vane is thin and the variation effects of vane dimensions on the mechanical efficiency of the compressor are less significant than other design variables. Therefore, the dimensions of vanes can be eliminated as design variables. The mechanical efficiency of the compressor is 0.55. The optimum values of these design variables are recommended for further development of the compressor.

A study on numerical optimization and performance verification of multiphase pump for offshore plant

2017 ◽  
Vol 231 (5) ◽  
pp. 382-397 ◽  
Author(s):  
Jun-Won Suh ◽  
Jin-Hyuk Kim ◽  
Young-Seok Choi ◽  
Won-Gu Joo ◽  
Kyoung-Yong Lee
Keyword(s):  
Performance Evaluation ◽  
Numerical Optimization ◽  
High Efficiency ◽  
Internal Flow ◽  
Latin Hypercube Sampling ◽  
Mechanical Efficiency ◽  
Optimal Point ◽  
Axial Pump ◽  
Design Variables ◽  
Single Objective

Multiphase pumps are core equipment for offshore plant industry. They are utilized in diverse areas. According to a report about the tendency of multiphase pumps for offshore plant, a helico-axial pump is the most preferred. A helico-axial pump with advanced technologies is widely known to have large handling capacity and operability even at high GVF ranges. However, its disadvantage is that its mechanical efficiency is lower than other multiphase pumps. Because of this, a numerical optimization was performed in this study to enhance the hydraulic performance of multiphase pumps. Before numerical optimization, reliability verification of numerical analysis for single-phase and multiphase flow was carried out. To perform a single objective optimization for high efficiency, design variables and ranges were selected. The single objective optimization was conducted for both impeller and diffuser. The objective function was evaluated at design points using Latin-hypercube sampling, one experiment technique, in design ranges. The performance of the experiment sets was evaluated using advanced computational fluid dynamics. After that, the response surface of a second-order polynomial function which was produced based on the performance evaluation results was used to find the optimal point. The results showed remarkable increases in a higher performance level than the base model. The reason for performance improvement was analyzed through comparison of the internal flow field. Additionally, numerical results were compared to results of performance evaluation through experiment.

High Pressure Air Compressor Condition Monitoring Using Unsupervised Pattern Classification Based on Projection Networks

2005 ◽  
Author(s):  
C. James Li ◽  
C. Jansuwan
Keyword(s):  
High Pressure ◽  
Supervised Classification ◽  
Clustering Algorithm ◽  
Unsupervised Classification ◽  
Single Class ◽  
Air Compressor ◽  
Classifier System ◽  
Discharge Valve ◽  
Air Compressors ◽  
Projection Network

High pressure air compressors (HPAC) are a high maintenance machine for they break down more often than expected and they serve critical roles. This study established the utility of an unsupervised pattern classifier system integrating a clustering algorithm based on DBSCAN and a dynamic classifier based on projection network to classify the condition of a 4-stage high pressure air compressor. The clustering algorithm is used to form clusters from un-labeled data and eliminate outliers. Subsequently, a system of projection networks is established to recognize all the significant clusters. The compressor data is consisted of pressures and temperatures at all four stages taken under various conditions including different baseline conditions, 3rd stage suction valve fault, 3rd stage discharge valve fault, and cylinder pitting and corrosion. The clustering algorithm was able to form clusters that each individually contains data mostly from a single class, and the projection network was able to differentiate these clusters and therefore classify the condition of the compressor correctly about 94% of the time. The ability of unsupervised classification does come with a price of lower classification accuracy. It was about 5% lower than what was accomplished by supervised classification.

Parameter Optimization of Compressor Based on an Ant Colony Optimization

2012 ◽  
Vol 201-202 ◽  
pp. 916-919
Author(s):  
Mei Peng Zhong
Keyword(s):  
High Pressure ◽  
Ant Colony Optimization ◽  
Low Pressure ◽  
Ant Colony ◽  
High Pressure Cylinder ◽  
Air Compressor ◽  
Pressure Cylinder ◽  
Set Up ◽  
Air Compressors ◽  
Particle Approach

A mathematical model of operation on air compressors is set up in order to improve the efficiency of air compressors. Parameter of Compressor is optimized by an Ant Colony Optimization (ACO) Particle approach. Volume and its weight of the new compressor are little, and its efficiency is high. An Ant Colony Optimization embed BLDCM module which optimizating the air compressor was put forward. Optimizated target of an Ant Colony Optimization is the efficiency of BLDCM. Optimizated variables are the diameter of low pressure cylinder, the diameter of high pressure cylinder, the journey of low pressure piston, the journey of high pressure piston and the rotate speed of BLDCM. Simulated result shows that the efficiency of BLDCM is more than that before optimizating. The test is done. The result shows that the specifc Power of air compressor is much less than before optimizating on 2.5Mpa. The result also shows that an Ant Colony Optimization which optimizating the air compressor is availability and practicality.

Finite Element Method and Parametric Study on Material Properties and Friction Coefficients for Design of Mechanical Components

2018 ◽  
Author(s):  
Yu Hua Li ◽  
Seung Ki Moon ◽  
Zhong Yang Chua ◽  
Teck Hui Ngo ◽  
Jun Jie Tou ◽  
...  
Keyword(s):  
Numerical Method ◽  
Material Properties ◽  
Parametric Study ◽  
Mechanical Efficiency ◽  
Von Mises Stress ◽  
Friction Coefficients ◽  
Air Compressor ◽  
Twin Screw ◽  
Von Mises ◽  
Screw Rotors

In this study, a parametric study on material properties and friction coefficient of mechanical components are investigated through simulating the real working conditions by a numerical method. As the screw rotors are the key components in an air compressor system, the rotors are exposed to complicated loading conditions during operation. The objective of this study is to investigate the effects on the input moment, peak Von Mises stress and the mechanical efficiency of the air compressor system subjected to varying parameters of the material properties of the female rotor and friction coefficients. From the simulation results, the peak Von Mises stress is greatly affected by the parameters of the material property of the female rotor, and the input moment and the mechanical efficiency are slightly influenced in the first condition. And, the peak Von Mises stress is significantly affected by the parameters of the friction coefficients, in the decreasing trend. The input moment is also increased with the increasing parameters of the friction coefficients. The mechanical efficiency is inversely correlated with the input moment, whereby efficiency is greatly reduced with an increase in input moment. The study shows that the proposed numerical method is efficient and suitable to establish the parameters study on the twin screw rotors, and provides an effective approach to investigate the twin screw rotors and improve the design of the system.

3D transient numerical simulation of a helical roots air compressor for FCVs

2021 ◽  
pp. 095440622110145
Author(s):  
Huan Wei ◽  
Linfen Xing ◽  
Bingqi Wang ◽  
Jianmei Feng ◽  
Xueyuan Peng
Keyword(s):  
Numerical Simulation ◽  
Fuel Cell ◽  
Simulation Model ◽  
Pressure Field ◽  
Volumetric Efficiency ◽  
Tip Clearance ◽  
Maximum Deviation ◽  
Air Compressor ◽  
Air Compressors ◽  
Transient Numerical Simulation

Oil-free helical Roots air compressors which have great application potential in air circulation systems for high-power fuel cell systems, such as commercial fuel cell vehicles (FCVs), have the advantages of active adaptation, low cost, large flow rate and high reliability. In this study, a three-dimensional transient numerical simulation model of a helical Roots air compressor was established by considering all leakage clearances. In this study, hexahedral structured dynamic grids were generated in the working chamber and the rotating angle was updated at an increment of 1° to ensure the mesh quality of the entire solving domain. The accuracy of the simulation model was validated using experimental data, and the maximum deviation was less than 4.0%. Based on the simulated results, the pressure field and variation of the pressure field with the rotation angle are presented. It shows that the pressure fluctuation at the discharge side was larger than that at the suction side. The influence of various leakage clearance on the volumetric efficiency was analyzed comparatively. Additionally, the flow field characteristic of clearance was revealed. It is found that the rotor tip clearance was the major factor for the reduction of volumetric efficiency when the size was larger than 0.12 mm instead of the interlobe clearance. It is suggested that more attention should be paid to control the clearance size to ensure the performance of helical Roots air compressors.

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